Development of a compact water activity sensor system for planetary exploration

Desai, Prarthana; Schmueser, Ilka; Dover, Coinneach Mackenzie; Underwood, Ian; Cockell, Charles S.

doi:10.1016/j.pss.2020.105132

Cited by 3 publications

(2 citation statements)

References 28 publications

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“…Such a measurement would contribute one aspect to an instantaneous habitability metric that could be determined by a planetary probe without requiring a complete understanding the full complexity of a planetary environment. This aligns with the ongoing development of miniaturized sensors that could, for example, measure ion concentrations and allow calculation of properties such as water activity (Shang et al 2019) or measure water activity directly (Desai et al 2021). Building such a metric would eventually lead toward a potential "habitability sensor."…”

Section: Introductionmentioning

confidence: 73%

The Water Activity of Mars-relevant Multicomponent Brines: The Changing Influence of Perchlorate on Habitability over Time

Stevens

Cockell

2023

Planet. Sci. J.

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Low water activity limits the habitability of aqueous environments, and salts present on Mars are known to reduce water activity. As environmental brines are not pure solutions of a single salt, predicting their water activity is difficult without direct measurement. Martian brines are likely complex and dominated by ions including sulfates and perchlorates, unlike typical terrestrial aqueous environments dominated by sodium chloride. We used the Pitzer model to predict the water activity of multicomponent brines and tested against laboratory-produced brines, including for the first time perchlorate salts that are known to exist on Mars. Our calculations match measurements of single-salt solutions and predict the water activity of multicomponent brines with an accuracy dependent on the quality of thermodynamic data available for a given ion combination. We tested the hypothesis that some salts will dominate the water activity, and therefore habitability, of multicomponent brines. Some salts, such as sodium and magnesium sulfates, did not strongly modulate the water activity of the solution, whereas others such as magnesium chloride and some perchlorates did. Applied to the history of Mars, the data suggest that sulfates and sodium chloride present in Noachian and early Hesperian environments would not have limited habitability. Perchlorates produced photochemically later in the Amazonian could impose a water activity limit at high concentrations that is not significantly changed by other salts. Overall we found that magnesium and calcium chlorides mixed with perchlorates can reach the lowest water activity values and therefore the lowest habitability of the brines tested.

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Section: Introductionmentioning

confidence: 73%

The Water Activity of Mars-relevant Multicomponent Brines: The Changing Influence of Perchlorate on Habitability over Time

Stevens

Cockell

2023

Planet. Sci. J.

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“…In addition, new and miniaturized technologies have been created by the field of astrobiology, and these can have important applications for studying life on Earth. These include miniaturised bioreactors, sequencers, spectrophotometers (Castro-Wallace et al, 2017;Massaro Tieze et al, 2021); sterilisation methodologies (Craven et al, 2021); a water-activity sensor (Desai et al, 2021); and protocols for life detection (Kminek et al, 2014;Abrahamsson et al, 2021). The articles presented in this special issue also contribute to our understanding of the nature and tenacity of life on Earth.…”

Section: Discussionmentioning

confidence: 99%

Astrobiology of life on Earth

Hallsworth

Mancinelli

Conley

et al. 2021

Environmental Microbiology

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Summary Astrobiology is mistakenly regarded by some as a field confined to studies of life beyond Earth. Here, we consider life on Earth through an astrobiological lens. Whereas classical studies of microbiology historically focused on various anthropocentric sub‐fields (such as fermented foods or commensals and pathogens of crop plants, livestock and humans), addressing key biological questions via astrobiological approaches can further our understanding of all life on Earth. We highlight potential implications of this approach through the articles in this Environmental Microbiology special issue ‘Ecophysiology of Extremophiles’. They report on the microbiology of places/processes including low‐temperature environments and chemically diverse saline‐ and hypersaline habitats; aspects of sulphur metabolism in hypersaline lakes, dysoxic marine waters, and thermal acidic springs; biology of extremophile viruses; the survival of terrestrial extremophiles on the surface of Mars; biological soils crusts and rock‐associated microbes of deserts; subsurface and deep biosphere, including a salticle formed within Triassic halite; and interactions of microbes with igneous and sedimentary rocks. These studies, some of which we highlight here, contribute to our understanding of the spatiotemporal reach of Earth'sfunctional biosphere, and the tenacity of terrestrial life. Their findings will help set the stage for future work focused on the constraints for life, and how organisms adapt and evolve to circumvent these constraints.

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